Configuration¶

The bridge is configured from a YAML file (default config.yaml, override with the -config flag or AGB_CONFIG) and/or environment variables. Environment variables always take precedence over the file.

Command-line flags¶

Flag	Description
`-config <path>`	Path to the YAML config file. Default `config.yaml`, or `AGB_CONFIG`.
`-version`	Print the version and Go version, then exit.

YAML file¶

server:
  port: 8080
  bearerToken: ""        # optional; empty disables authentication
  readTimeout: 10s       # HTTP read timeout
  writeTimeout: 30s      # HTTP write timeout; must exceed mail.sendTimeout
  shutdownGrace: 15s     # graceful shutdown budget

azure:
  tenantId: ""
  clientId: ""
  clientSecret: ""

mail:
  from: "monitoring@example.com"
  to:
    - "ops-team@example.com"
  subjectPrefix: "[alertmanager-graph-bridge]"
  template: modern       # e-mail layout: modern or classic
  saveToSentItems: false
  sendTimeout: 20s       # overall budget for delivering one webhook

log:
  level: info            # debug, info, warn, error
  format: json           # json or text

Durations accept Go-style strings such as 10s, 1m30s or 500ms. server.writeTimeout must be greater than mail.sendTimeout, otherwise the HTTP write deadline could fire while a slow Microsoft Graph call is still in flight; this is enforced at startup.

Environment variables¶

Every value can be supplied or overridden through an AGB_-prefixed variable.

Variable	Maps to	Notes
`AGB_CONFIG`	config file path	Default `config.yaml`
`AGB_SERVER_PORT`	`server.port`	Integer
`AGB_SERVER_BEARERTOKEN`	`server.bearerToken`	Empty disables auth
`AGB_SERVER_READTIMEOUT`	`server.readTimeout`	Duration
`AGB_SERVER_WRITETIMEOUT`	`server.writeTimeout`	Duration
`AGB_SERVER_SHUTDOWNGRACE`	`server.shutdownGrace`	Duration
`AGB_MAIL_SENDTIMEOUT`	`mail.sendTimeout`	Duration
`AGB_AZURE_TENANTID`	`azure.tenantId`	Required
`AGB_AZURE_CLIENTID`	`azure.clientId`	Required
`AGB_AZURE_CLIENTSECRET`	`azure.clientSecret`	Required; prefer env over file
`AGB_MAIL_FROM`	`mail.from`	Required, valid address
`AGB_MAIL_TO`	`mail.to`	Comma-separated list
`AGB_MAIL_SUBJECTPREFIX`	`mail.subjectPrefix`
`AGB_MAIL_TEMPLATE`	`mail.template`	`modern` or `classic`
`AGB_MAIL_SAVETOSENTITEMS`	`mail.saveToSentItems`	`true` or `false`
`AGB_LOG_LEVEL`	`log.level`
`AGB_LOG_FORMAT`	`log.format`

Validation¶

On startup the configuration is validated. The process exits with an error if:

server.port is outside 1-65535,
any of azure.tenantId, azure.clientId, azure.clientSecret is empty,
mail.from is missing or not a valid e-mail address,
mail.to is empty or contains an invalid address,
mail.template is not modern or classic,
log.level or log.format is not one of the allowed values,
server.writeTimeout is not greater than mail.sendTimeout.

Per-alert recipients¶

By default every alert goes to mail.to. An individual alert can override the recipients with an email_to label containing a comma-separated address list:

- alert: DatabaseDown
  labels:
    severity: critical
    email_to: "dba-team@example.com,oncall@example.com"

Alerts in a single webhook that resolve to different recipient sets are sent as separate grouped e-mails.

Addresses in an email_to label that are not valid e-mail addresses are dropped. If that leaves an alert with no explicit recipients, it falls back to the configured mail.to list, so a single typo cannot block delivery.

E-mail templates¶

mail.template selects the HTML layout of the generated e-mails:

Value	Description
`modern`	The default. A card-based layout with status badges, label chips and formatted timestamps.
`classic`	The look of the stock Prometheus Alertmanager e-mail: firing and resolved sections with plain label/annotation lists.

Both templates carry the same information and the same product branding; only the visual style differs.